If you are really ready for it, you should not be considering failure as an option. It will only stress you. You can do it, you know you can do it, and your instructors know you can do it. So just go and do it!
If your examiner asks you to do something stupid (mine did) just check he really means it, let him know you wouldn't be happy doing it in other circumstances, then if he insists, have a go. On my test it worked out OK, and I was left feeling that he probably knew it would, but he wanted to see whether I knew it was dodgy.
(I did check beforehand - and was assured that he is the commander for the flight, so you do what he asks.)
BTW before the flight, my examiner told me that things would go wrong (and he made sure they did!) and that I was to put them behind me as soon as they were resolved. I found that quite hard. But I passed.
Good luck - and believe me, it is only a licence to learn!
